Direct Comparison of the 0/1h and 0/3h Algorithms for Early Rule-Out of Acute Myocardial Infarction

myocardial infarction ◼ troponin P atients with symptoms suggestive of acute myocardial infarction (AMI) account for ≈10% of all emergency department (ED) presentations. 1 The majority of patients are finally found to have diagnoses other than AMI. 2 Thus, the expeditious evaluation of such patients is important because delays in ruling out AMI may interfere with the detection of other underlying diseases.The 0/1 hour (0/1h) algorithm and the 0/3 hour (0/3h) algorithm are both recommended by the European Society of Cardiology with a Class I recommendation for the early rule-out of AMI. 1 The 0/1h algorithm and 0/3h algorithm are completely different protocols.Whereas the 0/1h algorithm uses high-sensitivity cardiac troponin (hs-cTn) concentrations at presentation and absolute changes within the first hour and hence takes optimal advantage of the increased diagnostic accuracy and precision of hs-cTn assays, the 0/3h algorithm uses a fixed threshold protocol based on the 99th percentile at presentation and 3 hours in conjunction with clinical criteria (GRACE [Global Registry of Acute Coronary Events] score <140 and the need to be pain free).It is currently unknown whether 1 algorithm is preferable to the other.The aim of this study was to directly compare safety, quantified by the negative predictive value (NPV) and the negative likelihood ratio (LR) for the presence of AMI, and efficacy, quantified by the proportion of patients triaged toward rule-out in a large diagnostic multicenter study enrolling patients presenting with suspected AMI to the ED (URL: https://www.clinicaltrials.gov.Unique identifier: NCT00470587).The study was carried out according to the principles of the Declaration of Helsinki and approved by the local ethics committees.Written informed consent was obtained from all patients.Patients presenting with ST-segment-elevation MI were excluded.Triage toward rule-out by the 0/1h or the 0/3h algorithm was compared against the final adjudication performed by 2 independent cardiologists using all information, including cardiac imaging and serial hs-cTnT measurements.Analyses were performed with hs-cTnT and hs-cTnI.NPV and efficacy were compared by the McNemar test and Pearson χ 2 test, respectively.The 95% confidence intervals (CIs) were calculated with the Wilson score method without continuity correction.Among 2547 patients eligible for analysis with hs-cTnT, AMI was the final adjudicated diagnosis in 387 patients (15%).The 0/1h algorithm provided safety similar to that of the 0/3h algorithm (NPV, 99.8% [95% CI, 99.4-99.9]and negative LR, 0.01 [95% CI, 0.00-0.03]versus NPV, 99.7% [95% CI, 99.2-99.9]and negative LR, 0.02 [95% CI, 0.00-0.05])but allowed the rule-out of significantly more patients compared with the 0/3h algorithm (60% versus 44%; P<0.001).Among 2197 patients eligible for analysis with hs-cTnI, AMI was the final diagnosis in 327 patients (15%).The 0/1h algorithm provided higher safety compared with the 0/3h algorithm (NPV, 99.6% [95% CI, 99.1-99.9%]and negative LR, 0.02 [95% CI, 0.01-0.05]versus NPV, 97.8% [95% CI, 96.7-98.5]and negative LR,